(1)共同的联系
用于同一宗族的世代成员之间。

(2)相互的约束
指加固领主与封臣之间关系的封建效忠的约束。

• undivided right
• undres
• undue influence
• undue means
• undue return
• unearned income
• unearned increment
• unearned interest
• unearned premium
• unearned premium reserve
• unearned surplus
• U.N.E.F.
• unemancipated minor
• unemployment insurance
• unemployment relief arrangement
• unemployment tax
• unemployment trust fund
• unencumbered
• unenforceable contract
• unequal
• unequivocal
• U.N.E.S.C.O.
• unethical conduct
• unexpired term
• unfair comment